ABSTRACT Assessment of workplace physical exposures is a critical aspect of research into work-related musculoskeletal disorders (MSD) and other conditions that may be affected by workplace physical exposures, including vascular disease, pregnancy outcomes, cancers, and work disability. Job exposure matrices (JEMs) convert coded job titles into exposure estimates. While JEMs are frequently used in studies of occupational cancers, JEMs are underutilized to estimate workplace physical exposures in studies of musculoskeletal and other chronic diseases. In addition to their efficiency, JEMs have two additional advantages for such studies: they can decrease information bias between cases and non-cases, and they allow the estimation of exposure data when no such data are otherwise available. Using data from a recent large cohort of working age adults in France, our study will build a general population JEM to enable large-scale studies of associations between workplace physical exposures and chronic diseases; compare exposures derived from the French data to those from an American JEM; compare exposure estimates from both JEMs to observed exposures from a large American cohort study; validate the JEM in a French population dataset using known associations between physical exposures and MSD; and further validate JEM exposures by testing their ability to replicate known exposure response associations with incident upper extremity MSD in a large American cohort study. The overall goal of this study is to expand and validate the use of JEMs in order to provide the ability to add work exposures to the many US general population data sets that include health outcomes and job titles, but no other work exposure data. We will also create a French JEM that will greatly expand the ability of researchers to study the effects of workplace physical exposures on many health outcomes in an exciting new large longitudinal study of working age adults in France. This capability will spur additional studies of multiple health outcomes related to workplace physical exposures. Our proposed study is directly responsive to both strategic goals of the NORA Exposure Assessment Cross- Sector designated in the current NIOSH Priority Goals for Extramural Research: ?Develop or improve exposure assessment strategies to understand and prevent work-related illnesses and injuries,? and ?Develop or improve specific methods and tools to assess worker exposures to critical occupational agents and stressors.? The study is also relevant to goals of the NORA Musculoskeletal Disorders Program.